Signal receiving and translating apparatus



July 23, 1946. w, PLENSLER 2,404,401

SIGNAL RECEIVING AND 'IRANSLATING APPARATUS Filed Jan. 20, 1944 5 Sheets-Sheet 1 YNVENTOR. ALEXANDER w. PLENSLER ATTORNEY July 23, 1946. w. PLENSLER 2,404,401

SIGNAL RECEIVING AND TRANSLATING APPARATUS- Filed Jan. 20; 1944 3 Sheets-Sheet 2 FIG. 3 FIG. 4 FIG. 5

INVENTOR ALEXANDER W. PLENSLER ATTORNEY SIGNAL RECEIVING AND TRANSLATING APPARATUS Filed Jan. 20, 1944 5 Sheets-Sheet 5 FIG. 9

FIG. I2

.83? 0I OI O 801 9a i Q 76 I 8/ 9/ 5 100 93 I 90 mz/mr/m/ 79 96 FIG.

INVENTOR Q XW ATTORNEY ALEXANDER w. PLENSLER Patented July 23, 1946 i UNITED STATES PATENT OFFICE SIGNAL RECEIVING AND TRAN SLATING APPARATUS Alexander W. Plensler, Chicago, 111., assignor, by

mesne assignments to Belmont Radio Corporation, Chicago, 111., a corporation of Illinois Application January 20, 1944, Serial No. 518,956

9 Claims. (01. 177353) The present invention relates to control or sig- Conjunction W t the present p v d receiving nailing systems, and, more particularly, to imapparatus; provements in signal carrier receiving and trans- 2 schematically illustrates the present lating apparatus, proved receiving apparatus characterized by cer- It is an object of the present invention to protain features of the prese t inv t vide improved signal carrier receiving and trans- 3 is a p p a View of the improVed Vibralating apparatus which is exceedingly simple in y r device embodied i t t s tt al its structural arrangement and mode of operaparailils shown n tion, and yet is thoroughly accurate and reliable Fig. 4 is a side sectional view of the device in its selective response to difi'erent received shown in Fig. signals. Fig. 5 is a bottom plan view of the device shown It is another object of the invention to proin vide improved interrupted carrier receiving ap- Fig. 6 is a side view of the vibratory reed deparatus in which differently tuned vibratory ele- V ee e od d n he leeeiving app us shown ments of a vibratory reed system are selectively in controlled in accordance with the different fre- 7 illustrates t device Shown in 6 quencies at which a received carrier may be interwhen rotated through 0 from the positi n shown rupted to provide the desired signal translation. in a It is a further object of the invention to provide Fig. 8 illustrates the device shown in Figs. 6

improved receiving a ratu of th h t and 7 when this device is rotated through 180 scribed which is highly selective in its response from the p n shown in to received signals and yet is substantially nonig. 9 is an expl V w p a y in seetio responsive to noise or t th tr i i of illustrating the details of the device shown in physical shock to the vibratory reed system.

It is still another object of the invention to pro- 10 is a detail View of a modified Vibratory vide receiving apparatus of the character ded structure Which y be used in y of the scribed which includes so few parts and is so simillustrated Vibratory d devices; ple in its structural requirements that it lends 11 is a p P a w us ating a modiitself to the construction of a small portable unit fication of the vibratory reed device wn i which is entirely self-contained. Figs- 7 and an According t ti11 noth bj t of t inven- Fig. 12 is a side view of the device shown in tion, the apparatus is arranged in an improved manner such that operation of any one of the Referring w to t d w more reeds to a signal translating setting positively W i i a Figs- 1 and zihereofi the prevents peratio f the Other 186115 5 the signalllng system there illustrated comprises a tem to their respective signal translating settings. Signal transmitter in and the present improved In accordance with another feature of the in- Signal receiver H which may located at P ti t apparatus is arranged in a Simple cally separated points. In this system, the demanner, which is non-critical as to frequenc sired control or indication response in the reto utilize the first few signal pulses of a re- 49 ceiving apparatus H is produced by the space ceived signal of any frequency in the actuation radiation of a high frequency carrier Wave from the transmitting apparatus H), which may be intranslating setting, and to utilize the following terrulited at one of the seveyal different signal pulses of the signal to hold the actuated 2331 5 3 zfigg gg i gg a g x gi g: reed its Sign? translating setting for the produced at the receiving point. In the illus of li slgnal recepinon' trated arrangement, space transmission between The mvendon 190th as oljgamzatlon and the transmitting apparatus I0 and the receiving {method of operatlon tcgetner Wlth further apparatus I I is utilized in the production of the 360135 and advantages thereof, will best be underto desired ignal or Control indications t t stood by reference to the specification taken in ceiving point. t 111 b understood, h w connection with the accompa y d w ngs n that the illustrated receiving apparatus is equalwhich: 1y well adapted for use in the translation of a Fig. 1 schematically illustrates improved carsignal carrier received over a Wired signal chanrier transmitting apparatus adapted for use in nel.

of the corresponding vibratory reed to a signal In brief, the transmitting apparatus or transmitter I3 comprises a high frequency carrier cur rent oscillator I4 coupled to an antenna-ground circuit I2 and arranged to generate a high frequency oscillatory voltage which is interrupted at a predetermined audio rate on a frequency selective basis by means of a vibratory reed device 2 I. More in detail, the oscillator I4 comprises a three electrode electron discharge tube I8 having a frequency determining circuit l5 of the parallel resonant type, comprising the shunt connected inductance and capacitance elements IS and Il, coupled between the anode I80. and control grid ISg thereof through a carrier frequency coupling condenser l9. An operating bias for the control grid l8g is supplied by providing a grid leak resistor l9b which is connected between this grid and the cathode I80 through a carrier frequency choke inductance Illa. The tube I8 is of the filamentary cathode type, being provided with a cathode I 80 connected for energization from a small low voltage battery 2o. It will be understood that the oscillatory circuit I5 is tuned by means of the variable condenser I! to oscillate at the desired carrier frequency when space current flow is produced through the tube IS. The inductance element I 6 of this circuit is mutually coupled to the inductance element |2b of the antenna-ground circuit l2, thereby to provide an inductive path for the transfer of signal energy from the oscillator I4 to the antenna-ground circuit. A transformer 22 is utilized in conjunction with the vibratory reed device 2| to impress an audio frequency alternating voltage across the space current path of the tube I8 which is utilized to shock excite the oscillatory circuit l5 and to produce space current fiow through this tube during alternate half cycles of the audio voltage. To this end, the transformer primary winding 22a is arranged for pulse energization from a small low voltage battery 23 at any one of a plurality of different audio frequencies respectively equaling the natural vibratory frequencies of the tuned reeds El, 62, etc., embodied in the vibratory reed device 2|. Further to this end, the secondary winding 22b of the transformer 22 is connected between the anode !8a and cathode I80 of the tube I8 over a path which includes the upper half Ifia of the inductance element I5. A filter comprising a carrier frequency choke 25, serially included in this path, and a carrier frequency by-pass condenser shunting the winding 22b is provided [or excluding spurious carrier frequency voltages from the antenna-ground circuit [2. For the purpose of driving the vibratory reeds GI, 52, etc., the device 2| is provided with an electromagnet field structure 5| which includes a driving winding 55 arranged for energization from the battery 23 in series circuit relationship with the primary winding 22a of the transformer 22. Control of this circuit on a selective reed basis to provide for energization of the winding 22a at different pulse rates is accomplished by providing self restoring push button or key switches 26, 21, 3|, etc., individual to the several reeds of the device 2|.

As best shown in Figs. 3, 4 and 5 of the drawings, the vibratory reed device 2| comprises six different reeds GI to 66, inclusive, having six different natural vibratory frequencies representing six different rates at which the carrier output of the oscillator I4 may be interrupted. These reeds, which are formed of spring steel or a like magnetic material, are supported upon a non-magnetic base member which also provides sup-' end of this reed.

. six identified vibratory reeds.

port for the electromagnetic field structure 5I. More specifically, the three reeds GI, 52 and 63 are rigidly mounted at their heel ends upon an insulating member 59 by means of anchor screws file, 620 and 630, respectively. The member 59, which may be formed of a thermosetting plastic material such as Bakelite or the like, is in turn rigidly mounted upon the lower end of the base member 56 by means of assembly bolts 59a. In a similar manner, the three remaining vibratory reeds 64, 65 and 6B are rigidly mounted, by means of anchor screws 64c, 65c and 65c, upon an insulating member 6i] which is rigidly supported upon the opposite end of the base 53 by means of assembly bolts 66a.

Each of the identified vibratory reeds fixedly supports a contact element arranged for vibratory engagement with a stationary contact element supported upon the base 50. Thus, and as just shown in Fig. 4 of the drawings, a movable contact element 621) is pinned to the vibratory reed 62 adjacent the heel end of this reed and is provided at it'sfree end with a contact arranged for vibratory engagement with a contact carried L by a stationary contact element 62d. In a similar manner, the reed 65 carries a movable contact element 65'!) adjacent the anchored end thereof which is adapted for vibratoiy engagement with a stationary contact element 65b. The three sta" tionary contact elements individual to the reeds BI, 52 and 63 are pinned or otherwise fixedly mounted upon an insulating piece 61, which extends transversely across an opening 59 cut in the base 55 and is anchored to the base by means of assembly screws 61a. Similarly, the three stationary contact elements individual to the reeds 6d, 65 and 66 are pinned to an insulating piece 68, which extends transversely across a second opening H3 cut in the base 50 and is anchored to this base by means of assembly screws 68a. Adjusting screws 62!, 65], etc., individual to the six stationary contact elements and threaded through the insulating pieces 61 and 68 are provided to permit individual contact adjustment of the six sets of contacts 52c, 656, etc., individual to the six reeds. At its free or toe end, each of the six reeds is provided with a weight for determining the natural period of vibration thereof and hence its natural vibratory frequency. Thus, the reed 52 is shown in Fig. 4 of the drawings as being provided with a weight 6211 for the purpose indicated. Similarly, the reed 65 is provided with a larger weight 65a which is secured to the free It will be understood that weights of different sizes are used on the different reeds in order to provide for vibration of the reeds at different frequencies. Thus the reeds may be so weighted that they vibrate at frequencies spaced from each other by 20 cycles Within a frequency range extending from 30 cycles to cycles.

In the illustrated arrangement, the six reeds are adapted to be driven by the same electromagnetic field structure 5i and the driving forces are applied thereto at the free or toe ends thereof. To this end, the field structure BI is supported centrally of the base 55! and is provided with a magnetic circuit having parallel paths which respectively include the free end portions of the In brief, this field structure comprises a U-shaped magnetic member 52, the legs 52a and 52b of which extend transversely of the base and are provided with ends extending through openings 5'! and 58 in the base to project upwardly beneath the'reeds.

The leg 52a of this member is provided at its corners with. struck. out, parts- 520 which are clamped against the underside of the base by means of assembly screws 56.. The opposite leg 52b is similarly provided with struck out corner parts 52d which are likewise clamped to the underside of the base 50 by means of assembly screws; 56. The field structure 5| also includes a center leg 53 which is anchored. in an opening through the central base portion of the member 52. and is provided with an end 53a which projects through an, opening. in the base 50 and is disposed substantially between the: oppositely directed free ends of the .two sets of vibratory reeds. This center leg carries a winding 55 whichis, insulated therefrom by means of. a sleeve. and is confined between two insulating. end pieces in the manner illustrated; With the; described arrangement of the field, structure, it will be understood that two parallel flux paths, are provided which commonly include the center leg 53 and respectively include the legs 52a and 52b of the member 52. That flux path which includes, the leg 52a also includes in parallel the end portions of the three reeds SI, 62 and 63 as well as the air gaps between these reeds, the end 53a of the center le 53, and the upper pole face end of the leg. 52a. Similarly, that flux path which includes the opposite leg 52!) of the field structure also includes the end portions of the reeds 54, 55 and 56 and the air gaps between the identified reed portions the end 53a of the center leg, 53 and the upper pole face end of the leg 520. It will be understood, therefore, that when the winding 55 is excited to produce flux traversal of the two flux paths, the free ends of the sixreeds are attracted toward the pole face ends of the legs 52a and 5217. Each time the winding 55 is de-energized, the attractive force exerted on the free ends of the reeds is released, causing the reeds to swing through their respective normal positions to'offnormal positions away from the pole face ends of the legs 52a and 52b. It will be understood, therefore, that if the winding 55 is periodically energized at a frequency equaling thenatural vibratory frequency of any particular one of the reeds, this particular reed will be driven. at the stated frequency with the maximum amplitude permitted by the inherent resiliency thereof.

The remaining reeds, because of the non-matching relationship between their natural vibratory frequencies and the frequency of' periodic excitation of the winding 55, tend to remain stationary or to vibrate with only non-appreciable amplitude.

Briefly, to consider the operation of the trans mitting apparatus l0 it may be assumed that the vibratory reed- 62 is tuned to vibrate at a frequency of 110 cycles per second, and that a, carrier interrupted at this rate is to be transmitted to the receiving apparatus H. In order to initiate the operation of the transmitter ill to winding of. the device 22 is thus energized, all six of the vibratory reeds are attracted toward the pole faceends of the field structure legs 52a and 52b. Incident to the resulting movement of the reed 62, the above mentioned" path is completed through the contacts 626 and 21b to short circuit the winding 55. When the driving winding 55 is thus de-energized, the six reeds are released and swingv through their respective normal positions to opposed off-normal positions. As the reed 62 swings away from the pole face end of the leg 52a, the contacts We are opened to interrupt thev path short circuiting the driving winding 55 whereby this winding is again energized in series with the winding 22a. Thus the reeds are again attracted toward the pole face ends of the field structure leg 52a and 52b, with the result that after a predetermined short time interval the contacts 62s are again closed to recomplete the path for short circuiting the winding 55. From this point on, the manner in which. the reed 62 functions periodically to energize the winding 55 is exactly the same as explained above. It will be apparent from this explanation that When the winding 55 is initially energized, the contacts individual to all six of the reeds are closed. Since, however, only the switch 21 occupies its off-normal position, the winding 55 can only be short circuited through the contacts 626 of the reed 62. Thus the five parallel short eircuiting paths through the contacts controlled by the five non-selected reeds are held open at the contacts 26b, 3112, etc., of the five non-operated switches. After the periodic energization of the winding 55 under the control ofthe reed 62 is well established, vibration of the other five reeds is substantially arrested for reasons which will be fully apparent from the above explanation.

It will be evident that each time the contacts 626 are closed to short circuit the winding 55, the current flow through the primary winding 22a of the transformer 22 is increased. Conversely each time the contacts 628 are opened,

' serially to include the winding 55 in the circuit ill radiate a carrier interrupted at the particular I control or signal frequency indicated, the switch 21 is actuated to its off-normal position. In rethe frequency of vibration of the reed 62.

for energizing the Winding 22a, the current flow through the latter winding is decreased; During each interval of increase or decrease in the current traversing the winding 22a, an induced voltage of corresponding polarity is developed in the secondary winding 22b. It will be understood therefore that as vibration of the reed 62 continues, an alternating voltage is developed across the winding 22b having a frequency which equals During alternate half cycles of this voltage. the anode [8a becomes positive with respect to the cathode lB-c to permit space current flow through the tube l8 under the control of the voltage appearing upon the control grid 189. During the intervening voltage half cycles, the anode Illa. becomes negative with respect to the cathode Mic with the result that space current flow through the unidirectionally conductive tube I8 is arrested. Each time space current flow through the tube l8 occurs, the circuit 15 oscillates at the particular carrier frequency to which it is tuned. To this end, a portion of the oscillatory voltage developed between the terminals of this circuit, and more specifically that appearing across the portion |6b of the inductive element I6, is impressed between the control grid I89 and cathode l8c'of the tube l8 over a path which includes the coupling condenser [9 whereby oscillation of the circuit- 5 for the duration of the voltage pulse and at the resonant frequency thereof is sustained. It will thus be apparent that as alternate half cycles of the generated alternating voltage are positively applied to the anode 18a of the tube l3, corresponding'pulses of high frequency voltage are developed across the terminals of the oscillatory circuit l5. The oscillatory energy is transferred to the-antenna-ground circuit 12 for space radiation through the mutual inductance coupling between the two inductance elements 1 and I212.

From'the foregoing description it will be clearly apparent that so long asthe switch 2'! is held in its off -normal position to sustain the vibratory movement of the reed 52, a high frequency carrier interrupted at the frequency of vibration of this reed is radiated by the -antenna-ground circuit |2.- When this switch is released or manually restored to its normal position, the energizing circuit for the two windings 55 and 22a is interrupted at the contacts 21a, with the result that periodic space current flow through the tube 18 is arrested to 'stop the interrupted carrier radiation. Incident to the normalizing of the switch 21, the contacts 2119 are also opened to interrupt the path through these contacts for short circuiting the driving winding 55 of the field structure 5|. It will also be evident that the particular frequency of the alternating voltage developed across the winding 2% and hence the frequency of the carrier pulses radiated from the antenna ground circuit I2 depends upon the particular one of the switches 26, 21, 3i, etc., which is operated. Thus if the switch 3|, for example, is operated to its oif-norrnal position, the reed 65'i rendered operative to determine the frequency of carrier pulse radiation. Again if the switch Z5 is selected for operation, the reed 6! is rendered operative to control the frequency of carrier pulse radiation.

As indicated above, the signals radiated by the transmitting apparatus It are adapted to be translated into control or signal indications by the receiving apparatus l I. In brief, the "eceiving apparatus comprises a batteryoperated carrier frequency receiver 32 having an antennaground circuit l3, a pulse repeating relay 33, and a pulse translating vibratory reed device 36-. More specifically, the relay 33 is arranged to fol low the received carrier frequency pulses and to repeat these pulses to the driving winding 83 of the device 36 by intermittently opening and closing the circuit for energizing this winding from a small low voltage battery 35. For the purpose of holding any operated one of the vibratory reeds 90, 9!, 92, etc., embodied in the device 35 in an operated or signal translating setting during off pulse periods, a condenser 38 is provided which is arranged to be connected in shunt With the winding 83 through any one of the signal indicating lamps 39 to 45, inclusive, individually associated with the diiTerent reeds. Energization of these lamps under the selective control of the vibratory reeds is accomplished by providing a small battery 31 for this purpose. Preferably the receiver 32 i of the Well known superregenerative type embodying a radio frequency amplifier stage, a detector stage and a power amplifier stage, and utilizes tubes of the filamentary cathode type at the three stages thereof. When the receiving apparatus is utilized to receive signals transmitted by a transmitter of the type illustrated in Fig. 1 within a distance of several hundred yards, it has been found that completely favorable response may be obtained by employingv in the receiver three. tubes, one for each of the enumerated stages,which are entirely adequate to furnish the power required for operation of the relay 33, the winding of this relay being substituted for the primary winding of the output transformer in the output circuit of the power amplifier stage.

As best shown in Figs. 6, 7, 8 and 9 of the draw ings, the vibratory reeds 95, 9|, 92, 83,5d and 95 with'which: the device 35 is equipped are in the form of fiat springs having like transverse dimensions and are constructed of spring steel-or another magnetic material having the desired resilient properties. These reeds are supported at their heel ends upon a square block '15 ofinsulating'material. More specifically, the lower end of each reed 92 is clamped by means of a clamp ing screw 98 to one leg of an L-bracket 96, the opposite leg of which is clamped to the insulating block 19 by means of an assembly screw or bolt 51. The six reeds are divided into two sets of three, which are respectively disposed adjacent opposite side edges of the insulating block 79. This block and the reeds carried thereby are supported from the field structure of the device by means'of a supporting post 18. More in detail, the central portion of the block '59 is clamped to the end of thepOSt l8 remote from the field structure by means of an assembly screw which is threaded into the post '53. The field structure proper comprises a pair of pole'pieces Hand 11 and a core element 15. At its lower end, as viewed in Fig. 9 of the drawings the core element 15 is provided with a threaded portion 15a of reduced'diameter which is adapted to extend through a central opening in the pole piece 75 and to be threaded into an opening provided in the supporting post 18. At its upper end, the core element 75 is similarly provided with a threaded portion 15b of reduced diameter which is adapted to extend through an opening in the pole piece 11 and to receive an assembly nut thereon. The field structure is completed by providing a'winding 83 which is wound upon a spool consisting of the insulating parts 82, 85 and 86, and is mounted upon the'core element 15 between the two pole pieces 16 and H. The contact structure of the device comprises two conductive discs 8| and 81 formed of copper or other non-magnetic material, the first of which is insulated from the pole piece TE by means of a strip of insulating material 82 and is clamped between this pole piece and the disc end of the supporting post 18. This contact element is provided at opposite edges thereof with angularly extending contact points a, 91a, 92a, 93a, 54a and 9511 which individually underlie the reeds 90, SI, 92, 93, 95 and 95. Similarly, the contact element 8'! is constructed of copper or another non-magnetic conductive material and is clamped between the pole piece 11 and the adjacent end 86 of the winding spool. This contact element is also provided along opposite edges thereof with angularly extending contact points 901), Bib, etcjwhich respectively underlie the vibratory reeds Si, 92, etc. The identified contact points of the two contact elements 8| and 8'! may be formed by slitting each element inwardly from opposite edges thereof at spaced apart points therealong. For the purpose of suspending the device from a sup porting structure or mounting the device upo'n the chassis of the receiver unit, an L-bracket 8B is provided having one leg thereof clamped between the pole piece H and the assembly nut 89. 'Ihls bracket is preferably formed of a nonany of to impart different predetermined natural vibratory frequencies thereto. If desired, each reed may be equipped with a non-magnetic metal band [00 of the form shown in Fig. of the drawings, which is slidable longitudinally thereof to adjust the vibratory frequency of the reed to the desired value. This band,'after being properly positioned along the reed to establish the desired reed frequency, may be crim'pe'd at its edges or squeezed into tight clamping engagement with the reed, thereby to prevent changes in the reed frequency. The same frequency adjusting expedient may be employed in'calibratingthe reeds of the device 2'! to the. desired'frequencies.

More specifically considered, the six'reecls of the device 36 are tuned to vibrate at naturalfre quencies which respectively correspond to the natural vibratory frequencies of the six reeds embodied in the device 2|. Thus the vibratory frequency of the reed 90 may b precisely matched with the vibratoryfrequncy of the transmitting reed Bl, the reed 9| may be matched as to frequency with the reed 62, and so on. It'wlll be noted that the reeds are normally free to vibrate without contacting the contact points of the two contact elements 8i and 87. This feature is incorporated in the structure to insure precise selective response of the reeds to the driving forces imposed thereon during intermittent energization of the winding 83' at different he quencies. More particularly, the arrangement is. such that when any one of the reeds is vibrated with substantially full amplitude it will contact the associated contact points of the two lements SI and 81 substantially concurrently. To this end, the structure is so arranged that the gaps between the reeds and their respective associated contact points are successively greater for the reedsof successively lower frequency, therebyto allow for the greater amplitudes of vibration of the lower frequency reeds. Thus the gaps between the reed 93, for example, and the contact points 90a and 90b aregreater than the gaps between the reed of next higher natural vibratory frequency and its associated contact points The required gap spacesmay 'be obtained by bending the mounting pieces 96' to the'co'rrect angles. Also, the desired contact point adjustment may be obtained by bending each contact point with a pair of long nose pliers until the proper displacement is obtained between the point'and its associated reed.

In the structure shown in Figs. 6, 7, 8 and 9 of the drawings, adjustment of the contact points individual to the two'reeds SI and 94 necessitates insertion of the plier jaws beneath the outer reeds which are respectively associated with the two identified center reeds. In order to obviate this difiiculty and to provide for a greater number of reeds without any substantial increase in the overall size of the structure, the construction shown in Figs. 11 and 12 of the drawings may be used. In this construction, the parts 19, I6 and 11 are of like dimensions and are each provided with five edges of equal length. Similarly, the contact elements 8| and 81 are each provided with five edges of equal length and have two contact points projecting from each of the five edges thereof. The reeds 90, 9|, 92, 93, etc., are disposed around the structure'with two reeds extending longitudinally along each side thereof m ing a ot of t l rce n, a l s st cural' arran eme t perm y ne of the ntac pqin fi aiil i e or he two c n ac ele e s 81 d o be c s 'reesh for adjustment without the insertion of plier jaws beneathany of'the're s From the above explanation it will be understood thatin each ofthe two disclosed "embodiments of the vibratory'reed device 3?, the magneticcircuit' of the device commonly comprises the magnetic coreelement l5 and the two pole pieces 3 and 71, in combination'witha plurality of parallel flux paths through'the' vibratory ends of the several reeds. These fiui'r paths each inelude an air gapxbetween the end of the reed 'providii gthe, same and the opposed pole face of the pole piece I1, and a second air gap between the central portion of the reed and the opposing pole face'of the pole piece Ti It will be'understood, therefore, that when the Winding 83'isener'gized, all of the several reeds are attracted towardthe respective associated pole faces of the two pole pieces it; and Ti. Conversely, when the winding 83 is de-energized all of the reeds' are released for vibration through their respective normal positions to off-nomal positions-away from their respective associated polefaces. The time required for such movement is of course different for the different reeds because of the differences in the natural vibratory frequencies thereof. Accordin'gly, if the winding 83 is periodically energised at a frequency equaling the natural vibratory frequency of any selected one of the reeds, that particular reed will, after two or three current pulses through the winding 83, vibrate with substantially full amplitude, while the other reeds will be only partially vibrated. As a mun, the particular'reed which is being driven at its natural vibratory frequency will be actuated to its signal translating setting to'engage the associated contact points of the two contact elements Bland Bl before the other reeds can possibly attain the amplitude of vibration required to contact these elements; In other words; the out of phase forces acting upon the non-selected reeds when "the winding 83 is periodically energized at a rate not corresponding to the vibratory frequencies of these reeds, prevent these reeds from vibrating tive associated contact points.

In considering the operation of the receiving apparatus II it may be assumed by way of ex ample that the transmitter 19 is operating under the control of the vibratory reed 61' to radiate a carrier which is interrupted'at the particular frequency equaling the natural vibratory frequency of the vibratory reed 99. This signal is collected by the antenna-ground circuit i3; amplifie'd by the radio frequency amplifier section'of the receiver 32, detectedin the detector stage of this receiver, and the audio components, i. e., the current pulses appearing in theoutput circuit {of the detector, are amplif edthrough thepower amplifie stage of the receiver to be manifested as current pulses through the relay winding" 3'3. Thus, each time a carrier pulse is picked u with suificient amplitude to engage their respec the antehna-ground circuit l3, the relay 33is sufficiently energized to operate. Conversely, at the end of each carrier current pulse the relay 33 is tie-energized and 'restored' In'operatin'gand releasing, the relay 33 functions to repeat the re ceived carrier pulses to the driving Winding dibf the vibratory reed device 36. Thus when this relay initially operates, it'closes its contacts 3.4 to

ate ier 11' complete an obvious circuit for energizing the winding 83 from the battery 35. This circuit is obviously opened to de-energize the winding 83 each time the relay 33 releases to open its contacts 34. As the periodic energization of the winding 83 proceeds, the reed 90 is driven with constantly increasing amplitude until it is actuated to engage the contact points 90a and 9911. Approximately three current pulses occurring at the particular frequency of vibration of the reed 90 are required to build up the amplitude of vibration of this reed sufficiently to effect engagement thereof with the two identified contact points. Immediately the reed 90 engages the contact point 90a, an obvious circuit is completed for energizing the associated indicating lam 39 from the battery 31. Immediately the reed 30 engages the contact point 901) a path is completed through the filament of the lamp 39 for connecting the condenser 38 in shunt with L the driving winding 83 of the vibratory reed device 39. After this path is completed, the condenser 38 is charged from the battery 35 in shunt with the winding 83 during each received carrier pulse when the contacts 34 are closed. When these contacts are opened to interrupt the circuit for directly energizing the winding 83, the condenser 33 discharges through the winding 83 over a path which includes the filament of the lamp 39 and the contact point 901). This discharge current serves to maintain the winding 83 sufficiently energized during each off pulse period to prevent the reed 90 from being released. In other words, the discharge current traversing the winding 83 maintains sufficient flux flow through the magnetic circuit of the device 36 during the off pulse periods to hold the reed 99 in its at tracted position relative to the associated pole faces of the two pole pieces 16 and TI. The ma netic force thus produced is however insufficient to pull any of the other reeds 9|, 92, etc., toward its associated pole face with sufficient strength to bring the reed into engagement with its associated contact points. Moreover, the continuous current flow through the winding 83 Which results from the lock in of the reed 90 in its sigrial translating setting positively eliminates any tendency for the non-active reeds to continue vibrating. It will thus be apparent that the first few pulses of the carrier pulse train are utilized It may be pointed out that since the energization of the winding 83 during off pulse periods is accomplished on a condenser charge-discharge basis, this particular action is entirely non-critical insofar as the frequency of carrier pulse translation is concerned. The only apparent limitation upon this particular feature of the circuit is that the time constant of the condenser discharge path substantially exceed the duration of the off pulse period of maximum length, represented by the lowest frequency of carrier pulsing. It has been found that, with values of resistance and inductance usually encountered in coils of the type of winding 83, a condenser 38 of the electrolytic type and of ID microfarad capacitance is entirely satisfactory to produce the desired reed lock in action when audio pulse rates above twenty-five cycles are utilized.

It will be understood from the above description that any one of the remaining five reeds 9| to 95, inclusive, may be selectively actuated to its signal translating setting when the carrier pulse transmission is effected at a frequency equaling the natural vibratory frequency of the particular reed in question. Regardless of the particular reed selected, the reed lock-in action proceeds in the exact manner explained above after three or four pulses of the pulse train have been transmitted to the winding 83. It will also be apparent that immediately'any one of the six reeds is locked in its signal translating setting, the remaining five reeds are positively locked out to prevent the same from being operated to their respective signal translating settings. Also, each reed, when actuated to its signal translating setting, closes an obvious circuit for energizing the associated one of the signal lamps 39 to 45," inclusive. The reeds may obviously be employed selectively to control the energization of control devices of any desired type, other than the illustrated indication lamps 39 to 45, inclusive.

From the foregoing explanation it will be understood that the above disclosed control or signaling system is extremely simple in its arrangement and mode of operation, that both the transmitting and receiving units thereof may be constructed to form exceedingly compact self-contained units which-are readily portable to any desired location, and that no sources of current other than the small batteries illustrated are reof the system may be attributed to the fact that a plurality of carrier current pulses occurring at a particular and set frequency are required in order to actuate any one of the Vibratory reeds 90, 9|, etc., to its signal translating setting, and

. to the further fact that noise disturbances are not sufiiciently periodic in character to produce this reed response. Not only is the receiving apparatus substantially non-responsive to extraneous noise picked up by the antenna-ground circuit l3, but in addition is substantially non-responsive to physical shock transmitted to the vibratory reed device 36. On this point it will be noted that in the particular construction disclosed, the reeds are anchored or mounted at ,7; their heel ends and are positively driven at their toe ends.

translating setting. The same feature is incorporated in the vibratory reed device 2| of the transmitting apparatus l0, and in addition all of the circuits controlled by the transmitting reeds 6!, 62, etc., are entirely open so long as their associated switches 26, 21, etc., are at normal. With this circuit structure, inadvertent carrier radiation is positively prevented.

While one embodiment of the invention has been disclosed, it will be understood that various modifications may be made therein, which are within the true spirit and scope of the invention.

I claim: 1. In a system for receiving any one of a plu- :xgrality of signals of different predetermined frepredetermined frequencies, electromagnetic driv-'. 'mgmeans common to said reeds and operative to develop reed driving impulses of any one of said frequencies when energized at said one frequency, whereby all of said reeds tend to vibrate upon initial energization of said driving means and the one reed corresponding to the one frequency is vibrated with greater amplitude than the remaining reeds, means responsive to a received signal for energizing said driving means at the received signal frequency rate, and means responsive to the resulting vibration of the particular reed, which corresponds to the signal frequency rate, at a predetermined amplitude of vibration for substantially continuously energizing said driving means for the duration of signal reception, thereby to hold said particular reed in an off-normal position.

2. In a system for receiving a signal having a predetermined frequency, a vibratory control element having a natural vibratory frequency which substantially equals said predetermined frequency, means including an exciting winding for i utilizing the first received impulses of said signal to initiate vibration of said element, and means for utilizing the succeeding impulses of said received signal to excite said winding to hold said vibratory element in a predetermined off-normal position so long as said signal is received.

3. In a system for receiving a signal having a predetermined frequency, a vibratory control element having a natural vibratory frequency which substantially equals said predetermined frequency, means including an exciting winding for utilizing the first received impulses of said signal to initiate vibration of said element, and means responsive to vibration of said element with a predetermined amplitude for utilizing the succeeding impulses of said received signal to excite said winding to hold said vibratory element in a predetermined off-normal position so long as said signal is received.

4. In a system for receiving any one of a plurality of signals of difierent predetermined frequencies, a plurality of magnetic vibratory control reeds having dilferent natural vibratory frequencies which respectively and substantially equal said predetermined frequencies, electromagnetic means for driving said elements including a winding, means responsive to the reception of any one of said signals for energizing said winding with current pulses which occur at the received signal frequency rate, whereby all of said reeds tend to vibrate when signal reception starts and the one reed corresponding to the received signal frequency is vibrated with greater amplitude than the remaining reeds as the signal reception continues, a condenser, and means responsive to vibration of said one reed with a predetermined amplitude for connecting said condenser in shunt with said winding to be charged by said current pulse and to discharge through said winding during each off-pulse period, thereby to hold said one reed in an off-normal p sition and to eliminate any tendency of the remaining elements to follow the current pulses.

5. Frequency selective control means comprising a plurality of magnetic vibratory elements having different natural vibrating frequencies, electromagnetic means for driving said elements and including a winding, means for selectively energizing said winding with current pulses 00- curring at any one of said frequencies, whereby all of said elements tend to vibrate and the one element corresponding to the selected pulse frequency is vibrated with greater amplitude than the remaining elements, and means responsive to vibration of said one element with a predetermined amplitude for continuously energizing said winding with a current of sufiicient magnitude to hold said particular reed in an off-normal position.

6. Frequency selective control means comprising a plurality of magnetic vivbratory elements having different natural vibratory frequencies, electromagnetic means for driving said elements and including a winding, means for selectively energizing said winding with current pulses occurring at any one of said frequencies, whereby all of said elements tend to vibrate and the one element corresponding to the selected pulse frequency is vibrated with greater amplitude than the remaining elements, a condenser, and means responsive to vibration of said one reed with a predetermined amplitude for connecting said condenser in shunt with said winding to be charged by each current pulse and to discharge through said winding during each off-pulse period, thereby to hold said element in an off-normal position and to minimize any tendency of the remaining elements to follow the current pulses.

'7. A control device comprising a magnetic vibratory element having a predetermined natural vibratory frequency, electromagnetic means for driving said element including a winding, means for transmitting a train of current pulses to said winding at said predetermined frequency, whereby the amplitude of vibration of said element is built up to a predetermined value during the first few current pulses transmitted to said winding, and means responsive to vibration of said element at said predetermined amplitude for utilizing the remaining current pulses of the train to provide sustained energization of said winding, thereby to hold said element in any one of the off-normal positions to which it is vibrated.

8. In a system for receiving a signal having a predetermined frequency, a vibratory control element having a natural vibratory frequency which substantially equals said predetermined frequency, means for utilizing the first received impulses of said signal to initiate vibration of said element, and energy storage means for utilizing the succeeding impulses of said received signal to excite said Winding continuously to hold said vibratory element in a predetermined off-normal position so long as said signal is received.

9. In a system for receiving a signal having a predetermined frequency, a vibratory control elefnefit having a natural vibratory frequency which substantially equals said predetermined frequency, means for utilizing the first received impulses of said signal to initiate vibration of said element, contact means closable in response to vibration of said element with a predetermined amplitude, and energy storage means controlled by said contact means for utilizing the succeeding impulses of said received signal to hold said vibratory element in a predetermined off-normal position so long as said signal is received.

ALEXANDER. W. PLENSLER. 

